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In nowadays diesel engine, the turbocharger system plays a very important role in the engine functioning and any loss of the turbine efficiency can lead to driveability problems and the increment of emissions. In this paper, a VGT turbocharger fault detection system is proposed. The method is based on a physical model of the turbocharger and includes an estimation of the turbine efficiency by a nonlinear adaptive observer. A sensitivity analysis is provided in order to evaluate the impact of different sensors fault, (drift and bias), used to feed the observer, on the estimation of turbine efficiency error. By the means of this analysis a robust variable threshold is provided in order to reduce false detection alarm. Simulation results, based on co-simulation professional platform (AMEsim© and Simulink©), are provided to validate the strategy.

A major issue in the development of the future engines (diesel or gasoline) lies in the architecture and the control of the air intake system. In this context many setups are envisaged, and in particular the turbocharging systems are becoming more and more complex: variable geometry turbines, double stage turbochargers, variable geometry compressors… For these new architectures, the engine control strategies need to be modified in order to address the specific issues related either to the new system in itself or to its integration in the global engine. Renault and IFP have studied together, from a control point of view, the integration of a double stage turbocharger in a diesel engine. This paper presents the works undertaken during this study. The structure of the paper follows the different stages of the project.

Improving the simulation support in engine development projects is a very attractive way to reduce cost and duration of such projects while increasing the deliverable quality. Thanks to advanced models and specific know-how, this paper presents a new step which consists in the use of simulation as a virtual engine bench for control design when the real engine is not yet available. In a first part, the goals and requirements of such a simulation approach are described. Then, the specific case of a two-stage turbocharger Diesel engine application from an IFP-RENAULT control design study is presented. At first, the virtual bench design is detailed from a methodological point of view. The engine simulator development and its use as a virtual control bench are then described. The control strategies design is presented, but also the anticipation of potential limitations such as inadequate turbocharger behavior or system failure detection management.

Compressed natural gas (CNG) is considered as one of the most promising alternative fuels for transportation due to its ability to reduce greenhouse gas emissions (CO2, in particular) and its abundance. An earlier study from IFP has shown that CNG has a considerable potential when used as a fuel for a dedicated downsized turbo-charged SI engine on a small urban vehicle. To take further advantage of CNG assets, this approach can be profitably extended by adding a small secondary (electrical) power source to the CNG engine, thus hybridizing the powertrain. This is precisely the focus of the new IFP project, VEHGAN, which aims to develop a mild-hybrid CNG prototype vehicle based on a MCC smart car equipped with a reversible starter-alternator and ultra-capacitors (Valeo Starter Alternator Reversible System, StARS).

In the context of modern engine control, one important variable is the individual Air Fuel Ratio (AFR) which is a good representation of the produced torque. It results from various inputs such as injected quantities, boost pressure, and the exhaust gas recirculation (EGR) rate. Further, for forthcoming HCCI engines and regeneration filters (Particulate filters, DeNOx), even slight AFR unbalance between the cylinders can have dramatic consequences and induce important noise, possible stall and higher emissions. Classically, in Spark Ignition engine, overall AFR is directly controlled with the injection system. In this approach, all cylinders share the same closed-loop input signal based on the single λ-sensor (normalized Fuel-Air Ratio measurement, it can be rewritten with AFR as they have the same injection set-point.

Torque balancing for diesel engines is important to eliminate generated vibrations and to correct injected quantity disparities between cylinders. The vibration phenomenon is important at low engine speed and at idling. To estimate torque production from each cylinders, the instantaneous engine speed from the crankshaft is used. Currently, an engine speed measurement every 45° crank angle is sufficient to estimate torque balance and to correct it in an adaptive manner by controlling the mass injected into each cylinder. The contribution of this article is to propose a new approach of estimation of the indicated torque of a DI engine based on a nonstationary linear model of the system. On this model, we design a linear observer to estimate the indicated torque produced by each cylinder. In order to test it, this model has been implemented on a HiL platform and tested on simulation and with experimental data.